Appalachian Thorn Snail
Carychium clappi Hubricht, 1959
File Thorn Snail
Carychium nannodes G. H. Clapp, 1905
Floodplain Thorn Snail
Carychium riparium Hubricht, 1978
Identification: All but C. riparium are described at Dourson (2015). (Some images)
Characters for Carychium clappi: Shell, especially the last several whorls, sculptured with relatively strong, evenly spaced transverse rib-striae; parietal lamella bent sharply downward; shell long and slender and usually more than 1.5 mm in height; outer apertural lip usually with a thickening, but not a distinct tooth; shell generally larger, nearly always at least 1 .85 mm in height
Characters for Carychium nannodes: Shell without rib-striae, or striae weak and irregular; parietal lamella not deflected sharply downward; shell very small, 1.5 mm or less in height.
Characters for Carychium riparium: Shell without rib-striae, or striae weak and irregular; parietal lamella not deflected sharply downward; shell larger, 1.5 mm or more in length; shell narrow and conical, smaller (2.0 mm or less in height).
Status: These are three less-often found species of Thorn snails in Indiana, all in the southeast.